Noise in the interior of an aircraft may be generated from a number of sources, including the aircraft engines and other equipment; airframe or fuselage vibrations; airflow over the exterior skin of the fuselage; and fans and airflow in the environmental control systems (ECS). A high level of noise in the interior cabin spaces of the aircraft can have an adverse impact on cabin occupants. Noise may affect passenger comfort and limit communication among the crew and passengers. In addition, prolonged exposure to high noise levels may impair hearing.
The ECS in an aircraft may include ram air, cabin pressurization, conditioned air supply, avionics cooling, auxiliary power unit, recirculation, cockpit cooling, and cargo heating systems. Airlines and airplane manufacturers traditionally control noise in the ECS by integrating mufflers and silencers into the systems and by wrapping air ducts in noise-insulating batting. These methods, however, add weight, increase operating costs, reduce performance and range, and increase complexity of the overall aircraft systems.
It is with respect to these considerations and others that the disclosure made herein is presented.